Recently, thin and lightweight liquid crystal display devices have been used as display devices used for monitors of personal computers and display sections of mobile information terminals. Liquid crystal display devices of the TN (Twisted Nematic) or STN (Super Twisted Nematic) modes, which were conventionally common, have drawbacks of a narrow viewing angle. In order to improve the viewing angle, various display modes have been developed.
As a display mode having an improved viewing angle characteristic, the IPS (In-Plane Switching) mode described in Patent Document 1 or the MVA (Multi-domain Vertical Alignment) mode described in Patent Document 2 are known.
A display mode referred to as the CPA (Continuous Pinwheel Alignment) mode is also proposed (see, for example, Patent Document 3). In the CPA mode, one of a pair of electrodes facing each other with a liquid crystal layer of a vertical alignment type interposed therebetween has an opening or a cutout area. Liquid crystal molecules are oriented as being radially inclined, using an oblique electric field generated in an edge of the opening or the cutout area. Thus, high quality display with a wide viewing angle is provided.
Patent Document 1: Japanese Patent Publication for Opposition No. 63-21907
Patent Document 2: Japanese Laid-Open Patent Publication No. 11-242225
Patent Document 3: Japanese Laid-Open Patent Publication No. 2003-43525